Problem: 2 markers cost $2.96. Which equation would help determine the cost of 10 markers?
Solution: There are several equations that could help determine the cost, each with a slightly different approach. We know the cost of 2 markers. We want to know the cost of 10 markers. We can write the numbers of markers as a proportion: $\dfrac{2}{10}$ We know 2 markers costs $2.96. We can let $x$ represent the unknown cost of 10 markers. The proportion of these costs can be expressed as: $\dfrac{\$2.96}{x}$ The cost changes along with the number of markers purchased, and so the two proportions are equivalent. $\dfrac{2}{10} = \dfrac{\$2.96}{x}$